It was even colder across much of the mountain west this Monday morning, than on Sunday.  Following is a list of observed minimums:

Thayne ES                         -28
Double L Ranch                 -27
Etna ES                              -21
Osmond ES                        -21
Smoot                                 -21
Afton                                  -18
Alpine                                 -17
Star Valley Ranch              -14

Two reports from Auburn from truck thermometers reported -30

Other Reports

Peter Sink UT                                      -46
Hog Park WY (near Encampment)    -42
Maybell CO                                         -41
Albany WY                                          -41
13 W Kemmerer WY                          -36
Bondurant WY                                     -34
Driggs ID                                              -33
West Yellowstone MT                           -33
South Park(Jackson0 WY                   -32
Pinedale WY                                         -31 
Box Y Ranch                                         -29
Idaho Falls                                             -20
Salt River Summit                                 -14
Pocatello                                                -13

As cold as it was here in Star Valley, it could have been even colder if it had not been for cloud cover for part of the night.  Note from the temperature trace on the Thayne ES station, that from before midnight until 6am temperatures did not drop.  And then just prior to sunrise the clouds disappeared and the mercury plummeted to the final low of -28 just prior to 9am.

Thayne Elementary School temperature Saturday 01/12/13 to Monday 01/14/13.